Method and apparatus for heat treating articles with open end bores



March 29, 1960 D. R. voss ET AL 2,930,603

METHOD AND APPARATUS FOR HEAT TREATING ARTICLES WITH OPEN END BORES 5 Bi .1 51 y Filed May 3, 1957 2 Sheets-Sheet l J22 den 23-215 D022 12?. 30,55 fia azzfard OZfler March 29, 1960 D. R. voss Ei- AL 2,930,603

METHOD AND APPARATUS F'QR HEAT TREATING ARTICLES WITH OPEN END BORES Filed May 3, 1957 2 Sheets-Sheet 2 6% fiarzzeg METHOD AND APPARATUS FOR HEAT TREATING ARTICLES WITH DPEN END BORES Don R. Voss and Stanford R. OHaver, Indianapolis, Ind.

Application May 3, 1957, Serial No. 656,858

1 Claim. (Cl. 2664),

This invention relates to an improved process and apparatus for heat treating crankshafts and the like. More specifically the invention relates to a heat treating process and apparatus for heat treating crankshaft bearings having lubricating grooves or bores opening outwardly on the surface of the bearing to be treated.

In the heat treatment of crankshaft bearings by the induction heating method, an electrical inductor is generally positioned in a manner to encircle the cylindrical bearing surface. The conventional inductor includes a quench chamber having openings adapted to direct a quenching fluid in impinging action against the cylindrical surface of the bearing. Bearings thus treated generally include openings forming one end of an open end lubricating groove or bore which in the ultimate function of the crankshaft directs oil in suitable quantities under pressure to the bearing and to the portion of a cylinder block on which the crankshaft is journalled. Lubricating bores of this nature generally extend in diagonal relation from one journal bearing to a crankshaft bearing. The conventional heating and quenching by the aforesaid equipment usually results in an excellent surface hardened bearing with the exception that maintenance difliculties have been encountered due to cracking and fracture of the material immediately adjacent the open end of the lubricating bore. The reasons for the dilficulties encountered at this particular portion of the bearing is due to the fact that fine stress cracks develop around the opening during the hardening process. These stress cracks ultimately may cause fracture or failure of the bearing of the crankshaft. In order to eliminate stress cracks around the open end of the lubricating bore, it is desired to retard the heating and quenching process with respect to this particular portion so that the material immediately adjacent the open end of the lubricating bore is not hardened to as high a degree as the other portions of the surface. Various means have been utilized to retard the heating and quenching action at this particular location. One of these was the practice of driving a wooden plug into the open end of the bore and this plug served to retard the heating process and also prevent the quench water from hitting or impinging upon the surface in question in such a way that the heating and hardening procedure does not result in the fine stress cracks normally encountered without the utilization of this element. However, the insertion and removal of plugs is quite costly in view of the labor and difliculties encountered. It is a prime object of this invention, therefore, to provide an improved process and apparatus for retarding the heating and quenching of portions of an article which lie immediately adjacent the open end of a bore contained in said article.

A still further object is to provide an improved process of heat treating a crankshaft bearing wherein the impingement of a quenching fluid and the heating of a surface of the article is retarded thereby eliminating undesirable stress concentrations in portions of the article immediately adjacent a lubricating bore.

A further object is to provide an improved process for heat treating a crankshaft bearing, the process including the steps of directing a gaseous fluid under pressure against a localized portion of the crankshaft bearing immediately adjacent the open end of a lubricating bore thus retarding the heating and quenching operation at a localized point.

A still further object is to provide an improved fixture adapted to be quickly placed in position on a crankshaft bearing for directing a gas under pressure to a lubricating bore, the said bore discharging said gas outwardly of a bearing surface which is being heated and quenched in a heat treating operation.

Still another object is the provision of an electrical inductor having a suitable quenching arrangement, the said inductor and quenching arrangement also including an improved device adapted to direct a gas under pressure against a localized portion of an article which has its surface under heat treatment.

These and other objects will become more readily apparent from a reading of the specification when examined in connection with the accompanying sheets of drawings.

In the drawings:

Figure l is a side elevational view of a crankshaft having portions broken away in section and including an improved heat treating apparatus also shown in section;

Figure 2 is a cross-sectional view taken substantially along the line 2-2 of Figure 1;

Figure 3 is a cross-sectional view taken substantially along the line 3-3 of Figure 1;

Figure 4 is an elevational view of a crankshaft having bearing portions shown in section, the view also showing an improved heat treating apparatus in section for heat treating the said crankshaft; and

Figure 5 is a cross-sectional view taken along the line 5-5 of Figure 4.

Referring now to Figures 1 through 5, an article to be treated is generally designated by the reference character 10. The article comprises a crankshaft 11 having rod bearings 12 which normally suitably are journalled on journal portions of a conventional internal combustion engine block. The crankshaft 11 also comprises eccentrically positioned connecting rod main bearings 13 suitably connected to the bearings 12 by longitudinally spaced conventional cheeks 14. The crankshaft 11 is conventional in that an oil bore 151 is provided, the said bore extending diagonally and communicating with a bore 16 extending through each of the main bearings. The bore 15 opens outwardly on one surface of the bearing 12, as indicated at 17, and the bore 16 opens outwardly, extending completely through the bearing 13, as indicated at 18 and 19.

Referring now particularly to Figures 1 through 3, an inductor or conductor 20 is indicated in position for hardening the surface of one of the bearings 12. The inductor 20 comprises a quench chamber 21 having suitable quench openings 22 adapted to direct a quenching fluid against the outer surface of the bearing 12. The inductor includes attaching portions 23 which are suitably connected to a source of electrical energy for operating the inductor 20 in conventional fashion. The inductor also includes nipples 24 which are suitably connected to flexible tubing 25 extending to a suitable source of quench fluid under pressure.

A gas supply fixture is designated at 26. The fixture 26 includes a flexible U-shaped member or spring yoke 27 which is adapted to partially straddle or encircle one of the connecting rod main bearings 13. The spring yoke 27 has at one end a rubber plug 28 which is suitably tapered in cone fashion so that its end penetrates into one open end of the bore as indicated at 19 for suitably sealing the same. The spring 27 is also provided at Patented Mar. 29, 1960' its upper end with a similar rubber plug or fluid connecting means for engaging the open end of the bore 16 as indicated at 18. The plug 29 also comprises a bore or passage 30 which is in communication with a passage in a fitting 31. The fitting 31 is suitably connected to a flexible hose 32, the said hose extending to a source of air or other gas under pressure.

In the operation, the inductor 20, by means of a high frequency current, suitably heats the outer surface of the bearing 12 to a suitable transformation temperature. After the desired temperature is obtained, quench fluid is discharged through the quench openings 22 for suitably hardening the surface of the bearing 12. Simultaneously, however, with the heating and quenching of the hearing 12 air or gas under pressure is supplied to the bores 15 and 16, the air emanating or being discharged from the open end of the bore as indicated at 17. The discharge of this gas or air under pressure inhibits or retards the heating and quenching of a portion of the surface of thebearing 12 immediately adjacent the open end of the bore. Thus the said portion of said surface remains in a relatively less heat treated or hard ened condition, thus eliminating stress cracks which might normally otherwise occur as a result of the heat treating operation. The fixture 26 may be quickly removed after each heat treating operation and thus is effective to eliminate the undesirable characteristics which might otherwise occur as a result of a treating operation on the bearings of crankshafts having open end bores.

Figures 4 and show a modified form of the invention. The crankshaftbearing 12, in this modified form, is surrounded or encircled by means of an inductor 35 having a suitable quench chamber 36 and quenching openings 37. The inductor 35 also includes attaching portions adapted to support the inductor and to connect the same to a suitable source of high frequency current. The inductor 35 is also provided with suitable nipples 39 to which flexible tubing 40 is attached for supplying quenching fluid to the quench chamber 36. A fitting 41 in the form of a tube extends through the inductor 35, the said fitting including an opening 42 positioned immediately adjacent or in substantial registry with the open end of the bore 15. The fitting 41 may be suitably brazed in aligned openings 43 in the inductor 35. The fitting 41 is also suitably connected to a flexible conduit 44-. adapted to supply gas or air under pressure from a suitable source.

In the operation the inductor 35 and quench chamber 36 function in the same manner indicated above with respect to the inductor 20. Simultaneously with the heating and quenching operation air or gas under pressure is supplied to the fitting 41 and is discharged through the opening 42 against portions of the surface of the bearing 12 positioned immediately adjacent the open end of the bore 15. This discharge of air against the said portion of the surface effectively retards or inexcellent and suificient to accomplish the desired purpose.

However, of course, different gases may be utilized or additional fluids may effectively provide the similar result which is obtained by air. It is not intended to limit the invention to the utilization of any particular fluid substance since any medium which will inhibit or retard the heat treating by interfering with the heating and quenching of a localized point, will create the desired result. The process is obviously suitable to any quench hardenable material such as steel from which crankshafts are usually made.

Thus it is apparent that an improved method and apparatus has been disclosed for heat treating articles having open end bores. It must be understood that changes and modifications may be made without departing from the spirit of the invention or the scope thereof as defined in the appended claim.

What is claimed is: 2

Apparatus for heat treating a quench hardenable crankshaft having eccentrically positioned longitudinally spaced first and second cylindrical bearings, said first bearing having a transverse bore with opposite ends opening outwardly on a surface of said first bearing, said crankshaft including a second bore communicating at one end with said first bore and having its other end opening outwardly on a surface of said second bearing comprising; a U-shaped member, a closure plug connected to one end of said U-shaped member and adapted to provide a closure for one end of said first bore, a fluid connecting means connected to the other end of saidyoke, said fluid connecting means including a passage adapted to direct cooling fluid under pressure to another end of said first bore and to said second bore whereby said fluid is discharged from the open end of said second bore, and an electrical conductor encircling said second References Cited in the file of this patent UNITED' STATES PATENTS 2,213,241 Denneen et a1 Sept. 3, 1940 2,541,124 Strickland Feb. 13, 1951 Rennick Nov. 15, 1952 

